1. Field of the Invention
The present invention relates to an image forming apparatus such as a copier, a printer, and a facsimile machine, and more particularly, to an image forming apparatus provided with a cleaning device including a powder container.
2. Discussion of the Background
In general, an electrographic image forming apparatus, for example, a copier, a printer, a facsimile machine, etc., includes an image forming mechanism for forming an electrostatic image carrier on an image carrier, such as a photoconductor, for developing the latent image; a transfer member for transferring the developed image onto a recording medium; and a fixing member for fixing the image thereon. Typically, the image forming apparatus also includes a cleaning device to collect any residual toner adhering to the image carrier. The toner collected by the cleaning device is transported, for example, to a waste-toner container in the image-forming apparatus as waste toner.
In recent years, a need has arisen to make the image forming apparatus compact. However, the above-described image forming apparatus, in which the waste toner is transported from the cleaning device to the waste-toner container, requires a transporting mechanism to transport the waste toner from the cleaning device to the waste-toner container, and thus, the image forming apparatus body is complicated and increases in size.
Several approaches have been proposed to solve the above-described problem.
In one known method, a cleaning member that is attached to a housing of the cleaning device collects a waste toner. The waste toner is contained in a waste-toner container formed in an interior space of the housing. Since the waste toner collected by the cleaning member is contained in the waste-toner container in the cleaning device itself, the image forming apparatus can be simplified and reduced in size because it does not require a transporting mechanism.
Further, the waste-toner container includes an optical sensor that detects whether or not the waste-toner container is filled with waste toner. When the optical sensor detects that the waste-toner container is filled with waste toner, then, for example, the image forming apparatus displays on a display panel a message that prompts a user to replace the waste-toner container.
In another known method, an image forming apparatus includes a waste-toner container that includes a toner detection space provided separately from a main waste-toner containing space as a protrusion from a part of a sidewall of the waste-toner container. The toner detection space is continuous with the waste-toner containing space, and the waste toner overflows into the toner detection space from the waste-toner containing space when the waste-toner containing space is filled with waste toner.
An optically transmissive material is used for the sidewall forming the waste-toner detection space, and a light emitting part and a light receiving part of an optical sensor arrangement are located so as to sandwich the outside walls defining the waste-toner detection space. As the waste-toner container fills with waste toner, the waste toner enters the toner detection space from the toner containing space and blocks the light from the light emitting part to the light receiving part of the optical sensor, the optical sensor detects that the waste-toner container is filled with waste toner.
However, in the image forming apparatus having such a configuration, waste toner floating in the waste-toner container can adhere to the sidewall of the waste-toner containing space, blocking the light from the light emitting part to the light receiving part of the optical sensor. In this instance, the optical sensor detects that the waste-toner container is filled with waste toner in error, even through the waste-toner container is not filled with waste toner and the waste toner does not enter the toner detection space.
Moreover, the waste-toner detection space is formed as a projection beyond the part of the sidewall of the waste-toner container, thus increasing the size of the waste-toner container increases accordingly.
As the waste-toner container thus increases in size, the space that the waste-toner container occupies in the image forming apparatus grows larger and proportionally increases the size of the image forming apparatus, neither of which is desirable.